The present invention relates generally to fabrication of semiconductor devices, and more specifically to methods of fabricating a barrier cap layer for lines and vias.
The current practice uses a copper (Cu)-chemical mechanical polishing (CMP) to planarize the copper surface after filling the line/via by copper electrochemical plating. The Cu-CMP stops on the oxide. A post-CMP silicon nitride (SiN) overlying cap layer is a common integration approach as a barrier layer for the next damascene structure.
U.S. Pat. No. 6,114,243 to Gupta et al. describes: 1) formation of a copper interconnect; 2) a copper-CMP; 3) etch-back of the copper interconnect; and 4) formation of a conductive barrier layer.
U.S. Pat. No. 6,291,332 B1 to Yu et al. describes a reverse plating technique.
U.S. Pat. No. 6,093,647 to Yu et al. describes another reverse plating technique.
U.S. Pat. No. 6,297,158 B1 to Liu et al. describes a copper dual damascene process using electrochemical plating.
U.S. Pat. No. 6,274,499 B1 to Gupta et al. describes a dielectric cap layer over a copper interconnect.
U.S. Pat. No. 5,744,376 to Chan et al. describes a copper interconnect with a top barrier layer.
Accordingly, it is an object of the present invention to provide an method of fabricating barrier cap layers over lines and vias.
Other objects will appear hereinafter.
It has now been discovered that the above and other objects of the present invention may be accomplished in the following manner. Specifically, a substrate having an opening formed therein is provided. The substrate having an upper surface. A planarized metal structure is formed within the opening. The planarized metal structure being substantially planar with the upper surface of the substrate. A portion of the planarized metal structure is removed using a reverse-electrochemical plating process to recess the metal structure from the upper surface of the substrate. A barrier cap layer is formed over the substrate and the recessed metal structure. The excess of the barrier cap layer is removed from over the substrate by a planarization process to form the planarized barrier cap layer over the metal structure.